Download Reebop Lab - The Green Isle

Name _____________________
Date _________ Per _________
Reebop Lab
A reebop is a little marshmallow organism that has 14 chromosomes (7 pairs). It
reproduces sexually. Male reebops go through spermatogenesis to make sperm
and female reebops go through oogenesis to make eggs. The sperm and eggs
each have 7 chromosomes due to meiosis. When fertilization occurs, 7
chromosomes are given by each parent, and the baby reebop has 14
chromosomes. The reebop diploid (2n) number is 14 and the haploid (n) number
is 7.
Gregor Mendel considered the “father” of Genetics developed two laws of
inheritance.
1. Law of Segregation:
2. Law of Independent assortment:
Purpose:
1. To understand the process of meiosis, fertilization, and development
2. To understand the role of alleles in determining traits of an offspring
3. To understand the difference between genotypes and phenotypes
4. To observe and analyze Gregor Mendel’s laws of inheritance.
Materials:
large marshmallows
green pipe cleaners
paper chromosome set
small colored marshmallows
red & blue pushpins
toothpicks
thumbtacks
paperclips
Procedure:
1. Observe the mom and dad reebops that your teacher has provided for you.
A) Describe their physical characteristics.
___________________________________________________________
___________________________________________________________
2. Work in groups of 2 students. Decide who will represent each parent. Remove
the paper chromosomes from the envelopes. The “father” should lay the green
chromosomes out on the desk from largest to smallest. The “mother” should do
the same with the red chromosomes. You have just created a reebop
karyotype. Karyotyping is a technique used to analyze the chromosomes of an
individual.
B) How many chromosomes does each parent have? ________
Homologous chromosomes are pairs of chromosomes that are the same size
and shape and code for the same characteristics.
C) How many pairs of homologous chromosomes does each parent
have? ________
3. Notice the letters on each chromosome (ex. #1 A, a; #2 Q, q). These letters
(capitol and lower case) represent alleles. Alleles are different forms of a gene
for a specific trait.
D) Why does each reebop have two alleles for a given trait?
___________________________________________________________
4. Turn the chromosomes over so you cannot see them. Keep them in karyotype
order (in pairs, largest to smallest).
5. The "father" should arbitrarily take one green chromosome from each pair and
put it in a pile called "sperm."
E) Is the sperm diploid or haploid? ________________
F) What type of cell division makes sperm (mitosis or meiosis)? ___________
6. The "mother" should arbitrarily take one red chromosome from each pair and
put it in a pile called "egg" (or ovum).
G) Is the egg diploid or haploid? ________________
H) What type of cell division makes eggs (mitosis or meiosis)? __________
7. Put the extra chromosomes back into the correct envelope.
8. Now, reebop fertilization can occur. Join the sperm and egg (two piles of
chromosomes). A reebop zygote has been formed! Flip the chromosomes over
so you can read them and arrange them in karyotype order (in pairs, largest to
smallest).
I) How many chromosomes does your zygote have? ________
J) How does this compare to the number that each reebop parent had
(question B)? ________
K) Is the zygote diploid or haploid? ________________
L) What process has to take over after fertilization in order for the zygote
for it to develop into a baby reebop?
___________________________________________________________
9. Complete the table 1 below for your baby reebop by analyzing its
chromosomes.
 Record the letters on the chromosomes under "alleles."
 The alleles that the baby reebop inherited are called its genotype. If the
baby reebop has two of the same alleles (ex. #1AA or aa) it is pure for
that trait. If the baby reebop has two different alleles (ex. #1Aa) it is
hybrid for that trait.
 Use table 2 to determine the reebops phenotype. The phenotype is the
physical characteristic expressed due to the genotype.
Table 1 Baby Reebop
Chromosome
Alleles
(letters)

1
_____
_____
2
_____
_____
3
_____
_____
4
_____
_____
5
_____
_____
6
_____
_____
7
_____
_____
Genotype
Phenotype
(pure or hybrid)
(physical characteristic)
Use the key to construct your Reebop.
10. Place the red chromosomes back onto the mother's envelope and green
chromosomes back into the father's envelope.
11. Compare your baby reebop with three of its siblings. Is your reebop the
same or different than its siblings? ____________________________________
12. Place your baby reebop in the designated nursery area.
Discussion questions
1. Reebops have a diploid number (2n) of 14. Explain how the diploid
chromosome number is maintained from one generation to the next. (In other
words, why did the baby reebop have 14 chromosomes instead of 28?)
2. For any given trait, how many alleles does a baby reebop have? Support your
answer.
4. Children from the same parents are not exactly the same. Explain why this is
true based on the reebop activity.
5. The fact that the different alleles were separated during this process and
randomly combined during fertilization is an example of which Law of
Inheritance?
6. The gene for the number of antennae and the gene for nose color were
passed on independently of each other. This process represents which Law of
Inheritance?